Mechanical Rotary Shock Testing Machines

ABSTRACT

A linear and rotary shock-testing machine including: a base; a shaft rotatably and translationally movable relative to the base; a test disc for holding one or more specimens to be tested, the test disc being rotatable with the shaft; one of a cam and cam follower fixed relative to the base; and an other of the cam and cam follower fixed to the test disc, wherein the shaft being driven to provide a rotational shock to the one or more test specimens; and the cam is shaped such that the cam follower follows the cam to urge the test disc into a translational motion while rotating to provide translational shock to the one or more specimens.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Divisional Application of U.S. patent applicationSer. No. 15/698,610 filed on Sep. 7, 2017, which is acontinuation-in-part of U.S. patent application Ser. No. 15/256,674filed on Sep. 5, 2016, and claims the benefit to U.S. ProvisionalApplication No. 62/384,670 filed on Sep. 7, 2016, the entire contents ofeach of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a spin-shock testing machinefor subjecting the components to be tested to a rotary accelerationpulse of a prescribed amplitude and duration, and more particularly fortesting various devices and components of rifled gun-fired munitions aswell said munitions by subjecting them to similar launch spinacceleration pulses generated by the gun barrel rifling.

2. Prior Art

Munitions fired from guns with rifled barrels are subjected to highrotary acceleration pulse as they are accelerated in rotation to theirmuzzle exit spin rates, generally to achieve highly stabilized flight.Spin deceleration is also encountered as munitions impact the target. Asa result, all components of the munitions and the assembled munitionsitself must survive the said shock loading event due to the impartedhigh rotary acceleration pulse and be qualified to such severeenvironments.

Component testing for survivability during the firing and foroperational performance and qualification testing, particularly duringthe development phase, cannot usually be done in an actual environmenton complete assemblies. In addition to prohibitive cost involved,testing of components in actual environments would not provide therequired information for evaluating the component design and performanceand for optimizing its design parameters. In addition, in many cases theperformance of a component can only be determined while integrated in asystem or sub-system. For these reasons, laboratory simulations of theshock loading environments are highly desirable for testing individualcomponents, sub-assemblies and sometimes the complete system assembly.

Gun-fired munitions, mortars and rail-gun munitions are also subjectedto high-G linear (setback and set-forward) acceleration during thelaunch and upon target impact. In some applications, lateralacceleration shock is also considerable. As a result, all components ofthe system and the system itself must survive the said shock loadingevents and be qualified to such severe environments. For this reason,shock-loading machines that to varying degrees simulate firing setbackacceleration environments have been developed.

In the current state of the art, firing setback (linear) accelerationbased shock loading environments are simulated in the industry by one ofthe following methods:

-   -   1. Electro-Dynamic Shaker.

This method can accurately produce a desired shock response spectrum(SRS) within closely specified tolerances, but amplitude and frequencylimitations of the equipment greatly restrict its applicability.

2. Live Ordnance with System Structure.

Since the actual system structure and live ordnance are used, thismethod has the potential to produce a shock virtually identical to theexpected field environment. The cost of the test structure, however, isusually prohibitive. The use of live ordnance may have a widerepeatability tolerance, and does not easily allow the test levels to beincreased so that an adequate design margin can be assured. For the caseof gun-fired munitions, mortars and the like, the added problem is the“soft” recovery of the launched round to examine the state of thecomponents being tested. In certain case, telemetry of data may be usedto transmit back data related to the operation of certain components.However, in most cases it is highly desirable to examine the state ofthe components post firing. In addition, in many cases it is extremelydifficult if not impossible to measure/determine the effect of shockloading on many components for transmission to a ground station viatelemetry. Visual observation of the dynamic behavior of the variousmechanical elements and mechanisms and other components, such aselectrical and electronic and sensory elements, and their interactionwith the munitions structure, is almost nearly impossible in most cases.Such visual observations are highly desirable for determining theirdynamic behavior under shock loading, for identifying their modes offailure, and ultimately for the purpose of arriving at their optimaldesigns.

-   -   3. Live Ordnance with Mock Structure.

This method has most of the same features as the method “2” above,except that some cost savings are attributed to the use of a massmock-up structure. These savings may be negated by the need for sometrial-and-error testing to attain the desired component input, wheregeometric similarity was used in method “2” above to attain the sameresult. This method also suffers from the same shortcomings for testingcomponents of gun-fired munitions and mortars and the like as indicatedfor the above method “2”.

-   -   4. Live Ordnance with Resonant Fixture.

This method further reduces test cost, and is a candidate for generalpurpose testing, due to the use of a generic resonant plate fixture.Since live ordnance is used, all the very high frequencies associatedwith near-field pyrotechnic shock events are produced with this method.However, a great amount of trial-and-error testing may be required toobtain the desired component input. This method also suffers from thesame shortcomings for testing components of gun-fired munitions asindicated for the above method “2” and amplitude and duration of theabove method “1”.

-   -   5. Mechanical Impact with Mock Structure.

Mechanical impacts do not produce the very high frequencies associatedwith the stress pulse in the immediate vicinity of a pyrotechnic device.However, most components in a typical system are isolated by enoughintermediary structure such that the shock at the component location isnot dominated by these very high frequencies. Instead, the shock at thecomponent is dominated by the structural response to the pyrotechnicdevice, and has dominant frequencies which are typically less than 10KHz. For these components, a mechanical impact (e.g. using a projectileor pendulum hammer) can produce a good simulation of the pyrotechnicshock environment. Test amplitudes can easily be increased or decreasedby simply increasing or decreasing the impact speed. The shock level andduration can be controlled to some extent by the use of various padsaffixed at the point of impact. According to this method, attempt ismade to subject the structure containing the test components the impactinduced acceleration (shock) profile, which close to that experiencedwhen assembled in the actual system. The test conditions areexperimentally adjusted to achieve an approximation of the actualacceleration (shock) profile. In general, a large amount oftrial-and-error runs have to be made to achieve an acceptableacceleration (shock) profile. The characteristics and response of thevarious pads used at the impact point to increase the duration of theshock (acceleration) event is generally highly variable and dependent ontemperature and moisture. In addition, due to inherent design of suchmechanical impact machines and the limitations on the thickness of thepads that can be used at the impact point, high G acceleration peakswith long enough duration similar to those, e.g., experienced bymunitions fired large caliber guns or mortars, cannot be achieved. Forexample, to achieve a peak shock acceleration level of 5000 G with aduration of 4 milliseconds, the said pad deformation has to be well over0.6 meters (considering a reasonable ramp-up and ramp-down of 0.1 meterseach), which is highly impractical. It is also appreciated by thoseskilled in the art that for simulating firing (setback) acceleration formost gun-fired munitions and mortars, the peak acceleration levels cangenerally be well over the considered 5000 Gs with significantly longerdurations. It can therefore be concluded that the described mechanicalimpact machines do not accurately duplicate the shock profileexperienced by munitions during firing or target impact and are notsuitable for accurate shock testing of components to be used in suchmunitions.

-   -   6. Mechanical Impact with Resonant Fixture.

In this method, a resonant fixture (typically a flat plate) is usedinstead of a mock structure. This significantly reduces cost, and allowsfor general purpose testing since the fixturing is not associated with aparticular structural system. The mechanical impact excites the fixtureinto resonance which provides the desired input to a test componentmounted on the fixture. Historically, test parameters such as plategeometry, component location, impact location and impact speed have beendetermined in a trial-and-error fashion. In general, this methodproduces a simulated environment which has its energy concentrated in arelatively narrow frequency bandwidth. It should be noted here that asuitable resonant fixture for use in this method may also be a barimpacted either at the end or at some point along the length of the bar.This method is suitable for many applications in which the componentsare subjected to relatively long term vibration such as those induced bythe system structure. The method is, however, not suitable for testingcomponents of gun-fired munitions and the like since in such cases themunitions is subjected primarily to a single very high G setback orimpact shock with relatively long duration.

-   -   7. Air-Gun Testing Platforms.

In this method, the components to be tested are usually mounted in a“piston” like housing with appropriate geometry. In one method, the said“piston” is then accelerated by the sudden release of pressurized air oraccelerated by the rupture of a diaphragm behind which air pressure iscontinuously increased until the diaphragm is failed in sheared. Inanother type of air gun a similar air tight “piston” within which thecomponents to be tested are securely mounted is accelerated over acertain length of a tube by pressurized gasses. The “piston” is therebyaccelerated at relatively slower rates and once it has gained aprescribed velocity, the “piston” existing the tube and impactsdecelerating pads of proper characteristics such as aluminum honeycombstructures to achieve the desired deceleration amplitude and duration.The components are assembled inside the “piston” such that the saiddeceleration profile to correspond to the desired actual shock(acceleration) profile. In general, similar to the above method “5”, airguns can be used to subject the test components to high G shock(acceleration) levels of over 30,000 Gs but for durations that aresignificantly lower than those experienced by gun-fired munitions,mortars and the like. It can therefore be concluded that the describedmechanical impact machines do not accurately duplicate the shock profileexperienced by munitions during firing or target impact and are notsuitable for accurate shock testing of components to be used in suchmunitions. Air guns in which the said test component carrying piston issubjected to the acceleration pulse by the sudden release of pressurizedair or is accelerated by the rupture of a diaphragm, the air gun mayalso be provided with sections that applies rotary acceleration (spinacceleration) to the piston. However, similar to the indicated case oflinear acceleration pulses, the pulse durations that can be generatedare significantly shorter than those experienced by gun-fired munitionsand the like. It can therefore be concluded that the (spin) rotaryacceleration pulses that can be generated by current air guns do notaccurately duplicate the rotary shock profile experienced by munitionsduring firing or target impact and are not suitable for accurate rotaryshock testing of components to be used in such munitions.

-   -   8. Rocket Sleds.

Rocket sled is a test platform that slides along a set of rails,propelled by rockets. As its name implies, a rocket sled does not usewheels. Instead, it has sliding pads, called “slippers”, which arecurved around the head of the rails to prevent the sled from flying offthe track. The rail cross-section profile is usually that of a Vignolesrail, commonly used for railroads. Rocket sleds are used extensively inaerospace applications to accelerate equipment considered tooexperimental (hazardous) for testing directly in piloted aircraft. Theequipment to be tested under high acceleration or high airspeedconditions are installed along with appropriate instrumentation, datarecording and telemetry equipment on the sled. The sled is thenaccelerated according to the experiment's design requirements for datacollection along a length of isolated, precisely level and straight testtrack. This system is not suitable for testing components for gun-firedmunitions and mortars and the like since it can produce only around100-200 Gs.

-   -   9. Soft Recovery System Facility (SCat Gun)

In this system, the components to be tested are packaged inside a round,which is fired by an actual gun (in the current system located at theU.S. Army Armament Research, Development and Engineering Center (ARDEC)in New Jersey, with a 155 mm round being fired by a 155 mm Howitzerweapon with a M199 gun tube and 540 feet of catch tubes). The projectileis then recovered using a “Soft Recovery” system. The soft catchcomponent of the system uses both pressurized air and water to help slowdown the projectile. The first part of the chain of catch tubes onlycontains atmospheric air. The next section, 320 feet of the tubes,contains pressurized air, followed by an 80 feet section that is filledwith water. A small burst diaphragm seals one end of the pressurized airand a piston seals the other end. The piston also separates the waterand pressurized air sections. The burst diaphragm and piston arereplaced after each test fire. Once fired, the projectile achieves freeflight for approximately 6 feet and travels down the catch tubes,generating shockwaves that interact with the atmospheric air section,the burst diaphragm, the pressurized air section, the piston and thewater section. The air section is compressed and pushed forward andshock and pressure cause the piston move against the water, all whileslowing the projectile to a stop. Then the piston is ejected out of theend of the system, followed by the air and water, and finally theprojectile comes to rest in a mechanized brake system.On-board-recorders inside the projectile measure the accelerations ofthe projectile from the gun-launch and the catch events. This systemcurrently provides the means to subject the test components to asrealistic firing shock loading conditions, including the rotary (spin)acceleration shock loading pulse, as possible and provides the means toretrieve the round to examine the tested components. The cost of eachtesting is, however, very high, thereby making it impractical for usefor engineering development. The system is also impractical for use formost reliability testing in which hundreds and sometimes thousands ofsamples have to be tested and individually instrumented. It also takeshours to perform each test.

The methods 1-6 described above are more fully explained in thefollowing references: Daniel R. Raichel, “Current Methods of SimulatingPyrotechnic Shock”, Pasadena, Calif.: Jet Propulsion Laboratory,California Institute of Technology, Jul. 29, 1991; Monty Bai, and WesleyThatcher, “High G Pyrotechnic Shock Simulation Using Metal-to-MetalImpact”, The Shock and Vibration Bulletin, Bulletin 49, Part 1,Washington D.C.: The Shock and Vibration Information Center, September,1979; Neil T. Davie, “The Controlled Response of Resonating FixturesUsed to Simulate Pyroshock Environments”, The Shock and VibrationBulletin, Bulletin 56, Part 3, Washington D.C.: The Shock and VibrationInformation Center, Naval Research Laboratory, August 1986; Neil T.Davie, “Pyrotechnic Shock Simulation Using the Controlled Response of aResonating Bar Fixture”, Proceedings of the Institute of EnvironmentalSciences 31st Annual Technical Meeting, 1985; “The Shock and VibrationHandbook”, Second Edition, page 1-14, Edited by C. M. Harris and C. E.Crede, New York: McGraw-Hill Book Co., 1976; Henry N. Luhrs, “PyroshockTesting-Past and Future”, Proceedings of the Institute of EnvironmentalSciences 27th Annual Technical Meeting, 1981.

The aforementioned currently available methods and systems mostly fortesting components to be used in various systems that subject them tolinear acceleration (shock) events, except for the method and system “7”(air-gun testing platform) and “9” (Soft Recovery System Facility-SCatGun), that can apply high rotary (spin) acceleration shock loading pulseto the components being tested. The methods and systems “7” and “9”,however, suffer from a number of indicated shortcomings that make themunsuitable for testing components and systems during engineeringdevelopment and evaluation process for spinning gun-fired munitions andthe like.

For the case of method and system “7” (air-gun testing platforms),similar to the applied linear (setback) acceleration pulses, theduration of the rotary acceleration pulses are significantly shorterthan those experienced by gun-fired munitions and the like. It cantherefore be concluded that the (spin) rotary acceleration pulses thatcan be generated by current air guns do not accurately duplicate therotary shock profile experienced by munitions during firing or targetimpact and are not suitable for accurate rotary shock testing ofcomponents to be used in such munitions.

For the case of method and system “9” (Soft Recovery SystemFacility-SCat Gun), the cost of each testing is very high, therebymaking it impractical for use for engineering development. The system isalso impractical for use for most reliability testing in which hundredsand sometimes thousands of samples have to be tested and individuallyinstrumented. It also takes hours to perform each test.

In addition to the above shortcomings, the method and system “7”(air-gun testing platform) and “9” (Soft Recovery System Facility-SCatGun) cannot provide the means of visually observing (e.g., videorecording) the dynamic behavior of the various mechanical elements andmechanisms and other components, such as electrical and electronic andsensory elements, and their interaction with the munitions structure.Such visual observations are highly desirable for determining theirdynamic behavior under shock loading, for identifying their modes offailure, and ultimately for the purpose of arriving at their optimaldesigns.

SUMMARY OF THE INVENTION

A need therefore exists for the development of novel methods andresulting testing apparatus (rotary shock testing machines) for testingcomponents of spin stabilized gun-fired munitions and other devices andsystems that are subjected to high and long duration rotary accelerationpulsed (shock loading) during firing by rifled barrels. Such rotaryacceleration pulses that are experienced by gun-fired munitions,particularly larger caliber munitions, may have durations of up to 10-15milliseconds and may be used to accelerate the round to spin rates inexcess of 200-300 Hz.

A need also exists for methods that are not be based on the use of theactual or similar platforms, for example, firing projectiles carryingthe test components with similar guns such as the described in themethod “9” above, due to the cost and difficulty in providing fullinstrumentation which would allow testing of a few components at a time,thereby making the cost of engineering development of such componentsand their reliability testing which requires testing of a large numberof samples prohibitively high.

A need also exists for novel mechanical rotary shock testing machinesthat can provide the means of testing a large number of fullyinstrumented components in a relatively short time. This requires thatthe said mechanical shock testing machine allows rapid mounting of testcomponents onto the test platform while allowing relatively free accessto the said components, unlike the “piston” platforms used in air guns(aforementioned method “7”) or inside projectiles that are gun-launched(aforementioned method “9”).

The novel mechanical rotary sock testing must also provide highlypredictable and repeatable rotary shock loading (acceleration) profilefor testing the intended components so that the results can be used fordetailed analytical model validation and tuning; for predicting theperformance of the components in actual applications; and for providingthe required information for the design of the said components andoptimization of the developed designs.

Herein is described a novel method for the design of rotary shocktesting machines and the resulting rotary shock testing machines thatcan subject test components and systems to high rotary accelerationpulse (shock) of relatively long duration. The resulting rotary shocktesting machines are shown to address the aforementioned needs and areparticularly suitable for engineering development and testing ofcomponents to be used in spin stabilized munitions fired from guns withrifled barrels.

In addition, a need also exists for the development of novel methods andresulting testing apparatus (rotary shock testing machines) for testingcomponents of spin stabilized gun-fired munitions and other devices andsystems that are subjected to high and long duration rotary accelerationpulsed (shock loading) during firing by rifled barrels from theirstationary state in the gun breach to their gun barrel spin rate. Suchrotary acceleration pulses from their stationary state in the gun breachto their gun barrel exit spin rate that are experienced by gun-firedmunitions, particularly larger caliber munitions, may have durations ofup to 10-15 milliseconds and may be used to accelerate the round to spinrates in excess of 100 Hz.

In addition, since during firing of munitions in rifled barrels, themunitions is subjected to linear acceleration in the direction of itstravel inside the barrel as well as the aforementioned spin accelerationabout the direction of its travel, therefore it is also highly desirableto provide methods of designing and constructing shock loading machinesthat can impart a combination of linear acceleration shock loading aswell as spin acceleration shock loading to the munitions systems and/orits components to be tested.

It will be appreciated by those having ordinary skill in the art that inmunitions firing in rifled barrels, the spin acceleration rate and thelinear acceleration rates are related and are not independent and therelationship is dependent on the pitch of the rifling inside the barrel.It will also be appreciated by those having ordinary skill in the artthat in certain applications, spin acceleration may be provided to themunitions being fired inside or outside the barrel by means other thanrifling. The spin acceleration shock loading machines provided hereincan also be used to simulate such shock loading events for testingmunitions systems and their components.

A need also exists for the development of methods and resulting testingapparatus for testing components of spin stabilized gun-fired munitionsand other devices and systems in a combination of high rotary and linearacceleration shock loading similar to those experienced during firing byrifled barrels.

Also provided herein are methods for the design of rotary shock testingmachines and the resulting rotary shock testing machines that cansubject test components and systems to high rotary acceleration pulse(shock) of relatively long duration from their stationary state to theirfinal spin rate. Also provided are shock-testing machines that cansubject test components and systems to a combination of high rotary andlinear acceleration shock loading similar to those experienced duringfiring by rifled barrels. The resulting shock testing machines are shownto address the aforementioned needs and are particularly suitable forengineering development and testing of components to be used in spinstabilized munitions fired from guns with rifled barrels.

BRIEF DESCRIPTION OF THE DRAWINGS invention will become betterunderstood with regard to the following description, appended claims,and accompanying drawings where:

FIG. 1 illustrates the schematic of a cross-sectional side view of thebasic embodiment of the mechanical rotary shock-testing machine.

FIG. 2 illustrates the top view of the basic mechanical rotary shocktesting machine embodiment of FIG. 1.

FIG. 3 illustrates the schematic of the braking units of the basicembodiment of the mechanical rotary shock-loading machine of the presentinvention shown in the schematics of FIGS. 1 and 2.

FIG. 4 illustrates the schematic of the mechanical rotary shock-testingmachine of FIGS. 1 and 2 with a high-speed video camera to record thedynamic behavior of the components being tested.

FIG. 5 illustrates the schematic of a cross-sectional side view of thesecond basic embodiment of the mechanical rotary shock-testing machine.

FIG. 6 illustrates the schematic of the mechanical rotary shock-testingmachine of FIGS. 1 and 2 with an alternative braking unit for applyingequal and opposite braking forces to the rotary disc.

FIG. 7 illustrates the schematic of the braking units of the basicembodiment of the mechanical rotary shock-loading machine shown in theschematics of FIG. 6.

FIG. 8 illustrates the schematic of an alternative braking unit of thebasic embodiment of the mechanical rotary shock-loading machine shown inthe schematics FIG. 6.

FIG. 9 illustrates an embodiment of a spin acceleration shock-loadingmachine in which the testing platform disc is accelerated from itsstationary position to a prescribed spin rate at a preset accelerationrate.

FIG. 10 illustrates an embodiment of a shock-loading machine that isused to apply a combined spin and linear acceleration shock similar tothose experienced by munitions fired in rifled barrels.

FIG. 11 illustrates a view of a back surface of the testing platformdisc of the shock-loading embodiment of FIG. 10 showing a design andoperation of the linearly accelerating cam of this machine.

FIG. 12 illustrates a side view of the testing platform disc of theshock-loading embodiment of FIG. 10 as seen in the direction of thearrow shown in FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The basic design and operation of the mechanical rotary shock-testingmachine is shown in the schematic of FIG. 1 and is indicated as theembodiment 10. The mechanical rotary shock testing machine 10 isconstructed over a base plate 11, which can be made out of a heavy andthick steel plate which is firmly anchored to the machine foundation 12by at least four heavy anchoring bolts (13 in FIG. 2) that are farenough apart around the base plate to resist the high torque reactionpulses (shocks) in reaction to the rotary shock loading pulses generatedby the mechanical rotary shock testing machine 10. The top view of thisembodiment 10 of the mechanical rotary shock-testing machine is shown inFIG. 2. Certain relatively stiff shock absorbing elements (not shown)may be provided between the base 11 and the foundation 12 to preventdamage to the foundation structure. In heavier machinery, a relativelylarge (usually made out of reinforced concrete) foundation block (notshown) can be used with shock isolation elements having been positionedbetween the foundation block and the surrounding structure.

In the embodiment 10 shown in the cross-sectional and top views of FIGS.1 and 2, respectively, a rigid platform structure 14 is firmly attachedto the base plate 11 and is used to rigidly attach the rotary assemblyof the mechanical rotary shock-testing machine to the base plate 11 asdescribed below.

The mechanical rotary shock testing machine 10 is provided with a“testing platform” disc 15, over the frontal surface of which 16 thecomponents to be tested 17 are generally attached. The testing platformdisc 15 is rigidly attached to a shaft 18, FIG. 1, which is supported byone or more bearings 19. The shaft 18 is provided with a pulley 20,which is used to rotate the shaft 18 by an electric motor 21 via a belt22 and the motor pulley 23, FIG. 2. The electric motor 21 is firmlyattached to the base plate 11. The speed of the electric motor 21 can becontrolled by a computer (not shown) as is commonly done in variousmachinery. The shaft 18 can be made out of two sections, the aft sectionof which is connected to the front portion to which the testing platformdisc 15 is attached by a coupling 25 as shown in FIG. 1. The couplingcan also be a one-way clutch or can be provided with a one-way clutch sothat as the disc 15 is subjected to a deceleration pulse through theengagement of the provided braking mechanisms as described later in thisdisclosure, the aft section 24 of the shaft 18 and thereby the electricmotor and the motion transmitting pulley and belt system are disengagedfrom the testing platform disc 15. In practice, multiple bearing units19 can be used on each section of the shaft 18 to minimize itsdeflection and to allow it to be rotated at the highest operating speedthat the machine is designed to operate.

The testing platform disc 15 is provided with at least one braking units26, FIG. 2, the details of which is shown in the schematic of FIG. 3.The braking units 26 are designed to engage the testing platform disc 15very rapidly upon command and apply a nearly constant braking force andthereby a nearly constant decelerating torque to the testing platformdisc 15 as it rotates at certain speed as described in detail below.

The braking unit 26, a schematic of which is shown in FIG. 3, canconsist of a braking pad 27, which is fixedly attached to a rigidbacking plate 28. The backing plate 28 is fixedly attached to thesliding member 29, which can slide back and forth (to the right and tothe left as seen in the schematic of FIG. 3) in the linear bearing 30,which is fixedly attached to the base plate 11. The linear bearing 30may be constructed to be free to rotate about its longitudinal axis ormay be provided with guides or shaped (for example with a squarecross-section) to prevent it from rotating. In one embodiment, acompressive spring 31, which can consist of a set of Belleville washers,is provided between the backing plate 28 and the linear bearing. Beforeperforming a rotary shock-loading test, the compressive spring 31 ispreloaded in compression to a prescribed level and held in the preloadedposition by the tip 32 of the sliding locking member 33 which engagesthe provided member 35 on the sliding member 29. The sliding lockingmember 33 is constructed to slide up and down, as seen in the schematicof FIG. 3, inside the guiding bearing 34. The sliding locking member 33can be biased downward in the engaged position with the member 35 of thesliding member 29 by a spring (not shown).

The level of the aforementioned prescribed compressive preloading of thecompressive spring 31 is selected such that considering the gap betweenthe braking pad 27 and the engaging surfaces of the testing platformdisc 15, FIG. 2, once sliding member 29 is released by the pulling ofthe sliding locking member 33 in the direction of the arrow 36, theforce with which the braking pad 27 presses against the surface of thetesting platform disc 15 generates a desired level of friction forcewhile the disc 15 is rotating. It is appreciated that while the testingplatform disc 15 is rotating, the friction forces generated by the atleast one braking pad 27 would apply a rotationally decelerating torqueto the testing platform disc 15. In practice, depending on the combinedmoment of inertia about the axis of rotation of the testing platformdisc 15, the payload 17, the shaft 18 and the inertia contributed by thecoupling 25, and the desired rotary deceleration rate at which thepayload is desired to be tested, the required level of the braking padgenerated torque is determined.

The level of preloading of the compressive spring 31 may be adjusted inmany different ways. One simple method consists of placing shim platesof appropriate thickness between the compressive spring 31 and thelinear bearing 30. When the level of compressive preloading required isvery high, a hydraulic cylinder 37 with the piston 38 shown in FIG. 3and fixed to the base plate 11 may be used to pull on the sliding member29 until the tip 32 of the sliding locking member 33 can engage themember 35 and maintain the compressive spring 31 at the desiredpreloading level.

In an alternative embodiment, the braking unit 26 can be provided with ahydraulic or pneumatic cylinder 37, which is shown in FIG. 3 by dashedlines. The piston 38 of the hydraulic (pneumatic) cylinder is thenattached to the sliding member 29 and is used to drive the braking pad27 to engage the surface of the testing platform disc 15 and apply thedesired level of force corresponding to the aforementioned deceleratingtoque pulse. The hydraulic (pneumatic) pressure of the cylinder 37 isreadily provided by commonly used hydraulic (pneumatic) sources (notshown) with manual or automatic pressure adjustment capability which arewell known in the art. In general, pneumatic systems are preferable overhydraulic systems since they are less costly, easier to operate, cleanerand require less maintenance. However, hydraulic pistons can bepressurized to significantly higher pressures, thereby occupying lessspace.

One advantage of using hydraulically or pneumatically operating brakingunits is that they provide the means of rapidly varying the deceleratingtorque level that is applied to the testing platform disc 15. However,in general, braking unit 26 that operates with the preloaded springs 31,particularly when relatively small Belleville washers are used for thispurpose, can engage the testing platform disc 15 and apply the peakdecelerating toque significantly faster than is possible with pneumaticand even hydraulic systems due to the significantly lower inertia of itsmoving parts, noting that in pneumatic and hydraulic systems the inertiaof the piston as well as displaced air and hydraulic fluid must also beconsidered.

To perform a rotary shock testing of certain components 17, thecomponents are firmly mounted on the surface 16 of the testing platformdisc 15 as shown in FIGS. 1 and 2. The testing platform disc 15 can beprovided with patterns of threaded and pin holes for mounting thecomponents directly or via appropriate fixtures to the surface 16 of thetesting platform disc 15. The testing platform disc 15 with the mountedcomponents 17 is then balanced. For relatively low spin rates, gravitybased balancing (also referred to as static balancing in the art forvehicular wheel balancing) is usually enough. This can be done by slowlyrotating the disc in the direction of one-way clutch 25 disengagement,and stopping every around 10-15 degrees to see if the otherwisestationary wheel would begin to continue to rotate due to an imbalancemass. If so, the operator will keep rotating the wheel a few degrees ata time until the disc would not rotate any further. This process wouldposition the equivalent imbalance mass at its lowest elevation. Theprocess is made easier if the operator can quickly disengage the one-wayclutch 25, in which case the equivalent imbalance mass willautomatically settle to its lowest elevation position. The one-wayclutch 25 may, for example, be designed for quick disengagement byattaching it to the shaft 18 by a readily removable pin or key (notshown). A counterweight of proper mass can then be fixedly attached tothe testing platform disc 15 at one or two symmetrically positionedthreaded or through holes provided on the opposite side of theequivalent imbalance mass position to balance the testing platform disc15 assembly with the attached testing component 17.

It will be appreciated by those skilled in the art that the method ofbalancing the testing platform disc 15 assembly with the attachedtesting component 17 is very similar to that of balancing vehicularwheels. As such, when the rotary speed (spin rate) at which thedeceleration shock loading pulse is intended to be applied is high, thetesting platform disc 15 assembly with the attached testing component 17may be required to be balanced dynamically, such as following anaforementioned gravity (static) balancing, as it is commonly done forvehicular wheels.

Once the testing platform disc 15 assembly with the attached testingcomponent 17 is balanced, the one-way clutch 25 is re-engaged and thetesting platform disc 15 is accelerated very slowly to the rotary speed(spin rate) at which the prescribed deceleration shock loading pulse isto be applied to the component 17 that is being tested.

Once the testing platform disc 15 has reached its required rotary speed,the sliding locking member 33 is pulled in the direction of the arrow36, FIGS. 2 and 3, thereby releasing the sliding member 29 and causingthe at least one braking pad 27 to engage the surface of the testingplatform disc 15 with the prescribed force generated by the preloadedspring 31. The friction forces generated by the braking pads 27 in turngenerate the required torque to the rotating testing platform disc 15 todecelerate it at the desired rate.

When hydraulic or pneumatic cylinder 37 is used instead of the preloadedspring 31, the sliding member 29 is displaced by the piston 38 of thecylinder 37 towards the rotating testing platform disc 15. The brakingpad 27 will then similarly engage the surface of the testing platformdisc 15 and the torque required to decelerate the testing platform disc15 at the desired rate is thereby generated.

As it is indicated above and appreciated by those skilled in the art,the reason for using braking unit 26 that operate with preloadedBelleville washer type springs 31 is so that full braking torque can beapplied to the testing platform disc 15 very rapidly so that rotaryshock loading pulse experienced during munitions firing can be nearlyduplicated for testing various components used in munitions. It isappreciated that during firing of munitions in rifled barrels the rotaryshock loading pulsed is applied to the round within as little as 1-2milliseconds, which is not possible to achieve by hydraulically orpneumatically actuated braking mechanisms. In cases where significantlyslower application of the braking torque is acceptable, then floatingcaliper type disc brakes similar to those commonly used in vehicles canbe used. Such disc braking systems are well known in the art.

In general, the motor 21 is computer controlled and is provided with aposition and possibly a rotational velocity sensor to allow theapplication of the desired acceleration and velocity profile to bringthe testing platform disc 15 to the desired spin rate before theapplication of the deceleration pulse as previously described. It is,however, also possible to have the capability to continuously measurethe position, velocity and acceleration of the testing platform disc 15directly. Such measurements are direct measurements of the state of thetesting platform disc and the component being tested 17, but moreimportantly, they can be used to directly measure the deceleration pulseprofile that is applied to the component that is being tested 17. As aresult, the component itself does not have to be instrumented by inertiasensors such as accelerometers to measure the profile of thedeceleration profile. Such a sensor 40, FIG. 1, for measuring theposition, velocity and acceleration of the testing platform disc 15 canbe non-contact, such as optical sensors reading finely spaced lines onthe edge or side of the disc, similar to commonly used optical encodersor bar code readers. It will be appreciated to those skilled in the artthat in such optical sensors, for example when detecting the edge ofequally spaced lines drawn or otherwise formed on the side of thetesting platform disc 17 (parallel to the direction of axis of rotationof the disc), by increasing the number of lines over the disc periphery,and/or by using multiple rows of lines that are differently spaced,and/or by using multiple detectors that are properly spaced, as well asby using the time and velocity information between each detected lines,the resolution of the position, velocity and deceleration pulse profilemeasurements can be significantly increased. Such optical sensors andtheir operation and methods of increasing their measurement precisionare well known in the art.

Alternatively, instead of an optical sensor, the sensor 40 may be a gapmeasuring sensor with the side surface of the testing platform disc 15having been provided with linear or the like shallow grooves. Then aseach groove passes the sensor the sensor electronic would count thenumber of such passing and thereby together with time information candetermine the position, velocity and acceleration profile of the disc asa function of time. Such sensory systems and their computationalalgorithms for measuring linear and rotary position, velocity andacceleration in various machinery are well known in the art.

It will be appreciated by those skilled in the art that by using one ofthe above non-contact sensors 40 for measuring the rotational position,velocity and acceleration of the testing platform disc 15 as a functionof time, then the need for a more complex system of slip rings forpowering instrumentation fixed to the rotating testing platform disc 15and for data transfer is eliminated. However, if, in certainapplications, there is a need for sensory devices such as accelerometersto be mounted on the testing platform disc 15, then the rotary shockloading machine 10, FIGS. 1 and 2, may be provided with slip rings 39,which can be attached as shown in FIGS. 1 and 2, with one ring fixed tothe shaft 18 and the other ring fixed to the bearing 19, thereby beingkept fixed to the machine structure. In the embodiment, the shaft 18 ismade out of a hollow tubing and the wiring for power and data transferis then be passed from the slip ring component that is attached to theshaft 18 through a hole into the hollow shaft and out of the frontand/or back surfaces of the testing platform disc 15 for attachment tothe provided instrumentations.

It will be appreciated by those skilled in the art that during firing ina rifled barrel, munitions are subjected to a high acceleration pulse(shock loading). In the rotary shock loading and similar to commonlyused shock loading machines used to simulate firing setback accelerationfor testing various munitions components and systems, the componentbeing tested is subjected to a similar deceleration pulse profile, whichwould have similar effects on the dynamic and structural behavior of thecomponent 17 that is being tested.

In many cases, while subjecting the component being tested 17, FIGS. 1and 2, to rotary shock loading, it is highly desirable to observe thedynamic behavior of the various components and structure of thedevice(s) being tested. For this purpose, a high speed camera 41 may beprovided on a platform 42, which can be attached rigidly to the baseplate 11, as shown in FIG. 4 to record the dynamic behavior of themoving parts, structure and other parts of the component being tested17. To this end, the high-speed videoing may be synchronized with therotary shock loading pulse by providing a simple switching element (notshown) on the sliding locking member 33 or the piston 38 of the cylinder37, FIG. 3, to simultaneously initiate the rotary shock loading pulseand the video camera 41.

In the embodiment 10 of the mechanical rotary shock-testing machine,FIGS. 1 and 2, the testing platform disc 15 is used directly as abraking disc to generate the required rotary shock loading toque pulse.However, it might be desirable to have a separate braking disc so thatthe entire front and back surfaces of the testing platform disc 15 isavailable for mounting the testing components 17. The provision of aseparate braking disc allows the use of smaller diameter testingplatform disc 15, which is highly desirable, particularly for testingmachines designed for operation at high spin rates. In addition, weardue to the braking action of the braking pads on the surfaces of thetesting platform disc 15 is eliminated, thereby minimizing systemmaintenance requirement. This is particularly beneficial since separatebraking discs will be significantly cheaper than testing platform disc15 and the present mechanical rotary shock testing machine can bedesigned as described below, such that the braking disc can be readilyreplaced.

Such an embodiment 50 of the mechanical rotary shock testing machine ofthe present invention is shown in the schematic of FIG. 5. In theembodiment 50 of FIG. 5 all components of the mechanical rotary shocktesting machine are identical to those of the embodiment 10 of FIGS. 1and 2, except for the addition of at least one braking disc 43 asdescribed below. In this embodiment 50, the rotary shock loading isapplied to the component being tested 17 by the at least one brakingunit 26, FIGS. 2 and 3, but the braking forces are applied to theprovided at least one braking disc 43 instead of being applied directlyto the testing platform disc 15. The at least one braking disc 43 isfixedly attached to the shaft 18, FIG. 5, which can be as close aspossible to the testing platform disc 15 to minimize the torsionaldeflection of the section of the shaft 18 between the discs 43 and 15.The braking pads 27 of the at least one braking unit 26, FIG. 3, wouldsimilarly engage the surfaces of the braking discs 43 to apply thedesired rotary shock loading deceleration pulse to testing platform disc15, thereby to the component 17 which is being tested under rotary shockloading.

It will be appreciated by those skilled in the art that the sensor 40,FIG. 1, used for measuring the position, velocity and acceleration ofthe testing platform disc 15 may be positioned as indicated by thenumeral 44 in FIG. 5 to make the same measurements with theaforementioned optical or the method using the braking disc 43.

The braking units 26 shown in the schematic of FIG. 3 are designed toapply braking force to one or the other surface of the testing platformdisc 15 or independently to both sides of the said disc as shown in FIG.2. The braking units 26 similarly applies braking forces to one orindependently to both sides of the disc brakes 43 of the mechanicalrotary shock testing machine embodiment 50 shown in the schematic FIG.5. It will be, however, appreciated by those skilled in the art that thebest method of applying braking forces to a rotating disc is by applyingequal but opposite forces to the sides of the disc and with theresultant force being as collinear as possible so that they would notsubject the disc to a bending moment. As a result, the braking disc canbe relatively thin, thereby reducing the overall system moment ofinertia and the decelerating friction generated torque needed to apply aprescribed deceleration rate to the components being tested 17. Inaddition, the braking force that has to be provided by the preloadedsprings 31 or the hydraulic or pneumatic cylinder 37, FIG. 3, issignificantly reduced, thereby reducing the required structural strengthand therefore the inertia of the moving components of the braking units26, making it possible for the braking pads to fully engage the brakingdisc significantly faster.

The basic method of applying equal but opposite braking forces to arotating disc is well known in the art and are known as floating caliperor swinging caliper type brakes. Various types of such calipers havelong been used on bicycle rim brakes. They are also widely used in manyvehicle disc brakes. In such brakes, instead of the sliding member 29 ofthe braking units 26 shown in FIG. 3, which only allow the brake pad tomove straight in and out towards the rotating disc (15 in FIGS. 2 and 43in FIG. 5), a swinging caliper utilizes a single vertical pivot locatedsomewhere away from the axis of rotation of the disc as observed in thetop view of FIG. 2. This basic method of applying equal but oppositebraking forces to rotating disc is shown in the schematic of FIG. 6.

In the schematic of FIG. 6, the basic design of a swinging caliper typebraking unit 46, indicated by the dashed line rectangle, is shown aspositioned for braking the testing platform disc 15 of the mechanicalrotary shock testing machine embodiment 10 of FIGS. 1 and 2. It ishowever appreciated by those skilled in the art that such swingingcaliper type braking units 46 may be similarly used to apply equal andopposite braking forces to the at least one disc brakes 43 of theembodiment 50 of FIG. 5.

A swinging caliper type braking unit such as the unit 46 shown in FIG. 6consists of a pair of braking pads 47, which are mounted on backingplates 48. The backing plates 48 are in turn attached to relativelyrigid pressure application plates 49. In general, even though thebraking pad may be attached directly to the pressure application plates49, they are instead attached (usually by a firm adhesive) tointermediate backing plates 48 for ease of replacement. The pressureapplication plates 49 are attached to scissor-type mechanism links 52 ofthe swinging caliper type braking unit 46 by spherical or rotary (pin)joints 51. The two links 52 of the scissor-type mechanism are connectedtogether at the joint 53, the pin of which can be fixed to supportstructure 54, which is in turn fixedly attached to the base plate 11.Alternatively, a separate rotary joint may be provided under the rotaryjoint 53, with its pin being fixedly attached to the base plate 11 andserve as the aforementioned vertical pivot of the present swingingcaliper type braking unit 46. Now, by applying equal but opposite forcesto the end (“handle” of the scissor-type mechanism of the swingingcaliper type braking unit 46) as indicated by the location and directionby the arrows 55 and 56 in FIG. 6, then the breaking pads 47 will applyan equal and opposite force to the testing platform disc 15 (or to theat least one disc brakes 43, FIG. 5, when used). As a result, no bendingforces will be applied to the braking disc 15 (43), and the disc can bemade relatively thin and therefore light.

The equal and opposite forces 55 and 56 may be applied, for example, bya provided compressively preloaded spring 57, which is released when itis desired to apply the brake to decelerate the rotating disc aspreviously described. The brake release element may, for example, be asimple relatively rigid member (not shown) that is positioned betweenthe ends of the links 52 (above the compressively preloaded spring 57 asseen in FIG. 6), and is pulled out to apply the brake. An example ofsuch a release mechanism is shown in FIG. 7.

In the schematic of FIG. 7, the braking unit 46 of FIG. 6 is redrawnwith a spring preload retaining and release mechanism. The springpreload retaining and release mechanism consists of the added structures59, which can be integral to the links 52 of the scissor-type mechanismof the braking unit 46. A locking element 60 is then used to hold thelinks 52 in the desired preloading position of the compressive spring57. Then, the operator can initiate braking force application by simplypulling the locking element in the direction of the arrow 61, therebyallowing the preloaded spring to apply the prescribed braking force tothe rotating testing platform disc 15, FIG. 6, or the at least one discbrakes 43, FIG. 5. In this embodiment, the preloading force may beadjusted in several ways, depending on the amount of adjustment that isdesired, including the provision (or removal) of spacers of appropriatethickness between the compressive spring 57 and the surface of one orboth links 52. For relatively large compressive force adjustments, thenumber or size of Bellville washers and/or their stacking configurationmay be varied. It will be appreciated by those skilled in the art thatthe primary objective in choosing the appropriate method is to achieveminimal gaps between the braking pads 47 and the braking discs, so thatfull braking force application can be achieved in minimal time.

An alternative preloaded compressive spring based braking unit mechanismis shown in the schematic of FIG. 8. This mechanism configuration isconfigured to make adjustment of the preloading force of the compressivespring easier to achieve and making its adjustment not to affect thespacing of the braking pads 47, FIG. 6, with the testing platform disc15 or the at least one disc brakes 43, FIG. 5.

In the schematic of FIG. 8, the braking unit 46 of FIG. 6 is redrawnwith the aforementioned spring preload retaining and release mechanism.Similar to the embodiment of FIG. 7, the spring preload retaining andrelease mechanism is provided with the structures 59, which can beintegral to the links 52 of the scissor-type mechanism of the brakingunit 46. A bolt 62 is passed through holes provided in the links 52 asshown in FIG. 8. The holes in the links 52 are slightly larger than thediameter of the passing bolt 62 so that it can freely move back andforth and rotate relative to the links. The preloading compressivespring 63 is then mounted over the threaded end 64 of the bolt 62against the outer surface 65 of the link 52 as shown in FIG. 8. A loaddisturbing washer 66 can be provided over the preloading compressivespring 63 and the nut 67, which is used to apply the required preloadingforce level to the compressive spring 63 and adjust its level to thedesired level. Before beginning the process of adjusting the preloadinglevel of the compressive spring 63, a release member 68 is positionedbetween the inner surfaces of the structures 59 of the links 52. Thewidth of the release member 68 is selected such that the braking pads47, FIG. 6, clear the surfaces of the testing platform disc 15, FIG. 6,or the at least one disc brakes 43, FIG. 5. It will be appreciated thatwith this design configuration, the operator can readily adjust thepreloading force level of the compressive spring 63 and when neededchange the size, the number and stacking order of the Bellville washersthat can be used in its construction. The used may obviously use anyother type of compressive spring or a combination of various spring(elastic or even elastomeric) elements for this purpose. The operatorcan then initiate the braking force application by simply pulling therelease member 68 in the direction of the arrow 69, thereby allowing thepreloaded compressive spring 63 to apply the prescribed braking force tothe rotating testing platform disc 15, FIG. 6, or the at least one discbrakes 43, FIG. 5.

For the sake of safety, it is appropriate that the locking element 60 inthe embodiment of FIG. 7 and the release member 68 in the embodiment ofFIG. 8 be pulled away in the direction of the indicated arrows toinitiate the braking actions by long enough cables or other similarmeans to ensure safe operation of the machine in high rate rotarydeceleration testing of various components, particularly those ofmunitions fired by rifled gun barrels.

It will be appreciated by those skilled in the art that in a mannersimilar to swinging caliper type braking mechanisms used in vehicles,one may use a hydraulic or pneumatic cylinder in place of thecompressively preloaded spring 57 shown in FIG. 6 to apply the indicatedequal and opposite forces 55 and 56 to brake the rotating testingplatform disc 15, FIG. 6, or the at least one disc brakes 43, FIG. 5.One may even use a cable as used in bicycle caliper type rim brakes.Hydraulic pistons have the advantage of being capable of applying verylarge braking forces and are very easy to adjust the braking forces tothe desired level and are the preferred method of braking forcegeneration as long as they can apply the braking force fast enough toachieve the desired few millisecond application time experienced bygun-fired munitions in rifled barrels. The required pneumatic pistonswill be significantly larger than hydraulic cylinders and will besignificantly slower than hydraulic cylinders in applying the brakingforces. However, if the required braking force levels and applicationtimes are acceptable, they are preferable to hydraulic cylinders due totheir ease of use, force adjustment, maintenance and service as well ascost. The use of cables with bicycle caliper type rim brakes ispossible, but only if the total moment of inertia of the rotatingtesting platform disc 15 and its other rotating components is relativelylow since the amount of braking force that can be applied by such cablesis relatively low and the brake activation time is relatively long.

In general, when very fast braking force application is desired, themethod of braking can be based on using preloaded springs, such aspreloaded compressive springs as shown in the schematic of FIG. 7. Thismethod is preferred since compressively preloaded springs constructed byproper stacking of Bellville washers or the like can generate therequired very high braking forces very rapidly by releasing the links ofthe braking unit scissor-type mechanism, for example, by the pulling ofa locking element 60 as previously described. Bellville washers arerelatively light, exhibit very high spring rate (constant), therebyrequire very short deformation to provide a very high preloading andtotal force application upon release. As a result, the braking unit canreact very rapidly to the release of its preloading mechanism.

The level of required friction forces that the braking pads 27 and 47,FIGS. 3 and 6, respectively, must apply to the surfaces of the rotatingtesting platform disc 15, FIG. 6, or the at least one disc brakes 43,FIG. 5, to generate the required decelerating toque is dependent on thecoefficient of friction between the braking pads and the contactingsurfaces of the discs, and the effective disc radius R_(e) as shown inFIG. 2, at which the resultant friction force is applied. If themagnitude of the effective equal and opposite forces applied by theabove braking pads is F_(e) and the coefficient of friction between thesaid braking pads and the surfaces of the said discs is μ, then thedecelerating (braking) torque τ applied to the rotating testing platformdisc 15, FIG. 6, or the at least one disc brakes 43, FIG. 5, is given by

τ=2μF_(e) R_(e)   (1)

The factor 2 in equation (1) is included to account for the fact thateach of the two braking pads is applying the same effective force F_(e).Now if for the embodiment of FIGS. 1 and 2 the combined moment ofinertia about the axis of rotation of the testing platform disc 15, thepayload 17, the shaft 18 and the inertia contributed by the coupling 25and other components rotating with the said disc is given as I_(e), thenby the application of the torque τ, equation (1), the testing platformdisc 15 is decelerated at a rate α_(d) given by

$\begin{matrix}{\alpha_{d} = \frac{\tau}{I_{e}}} & (2)\end{matrix}$

If the initial rotary speed of the testing platform disc 15 is ω, thenwith the applied deceleration rate of α_(d), equation (2), the length oftime t that will take for the testing platform disc 15 to be brought toa complete stop is

$\begin{matrix}{t = \frac{\omega}{\alpha_{d}}} & (3)\end{matrix}$

The same relationships apply to all embodiments, such as the embodiment50 of FIG. 5, assuming that proper effective radii R_(e) and effectiveforce F_(e) are used.

In the spin acceleration shock testing machines described above anddiscussed with regard to FIGS. 1-8, the spin acceleration occurringduring firing of spin stabilized rounds is simulated by the spindeceleration of a spinning test object. Also provided herein are spinacceleration shock loading machines in which the testing platform disc(15 in the embodiments of FIGS. 1, 2, 5 and 6) is accelerated from itsstationary position to a prescribed spin rate at a preset accelerationrate. Such spin acceleration shock testing machines and the resultingbasic apparatus embodiments are described below with regard to FIGS.9-12.

Apparatus and methods for such spin acceleration shock loading machinesin which the testing platform disc is accelerated from its stationaryposition to a prescribed spin rate at a preset acceleration rate isdescribed with regard to a spin acceleration shock loading machineembodiment 70 of FIG. 9.

A top view of the mechanical rotary shock testing machine embodiment 70is shown in FIG. 9. The mechanical rotary shock-testing machine 70 isconstructed over a base plate 71, which can be made out of a heavy andthick steel plate, which is firmly anchored to the machine foundation 72by at least four heavy anchoring bolts 73. The anchoring bolts 73 arepositioned far enough apart around the base plate 71 to resist the hightorque pulses (shocks) in reaction to the rotary shock loading pulsesgenerated by the mechanical rotary shock testing machine 70. Certainrelatively stiff shock absorbing elements (not shown) may be providedbetween the base 71 and the foundation 72 to prevent damage to thefoundation structure. In heavier machinery, a relatively large (usuallymade out of reinforced concrete) foundation block (not shown) can beused with shock isolation elements having been positioned between thefoundation block and the surrounding structure.

Similar to the embodiment 10 shown in the cross-sectional and top viewsof FIGS. 1 and 2, respectively, a rigid platform structure 74 is firmlyattached to the base plate 71 and is used to rigidly attach theindicated rotary assembly of the mechanical rotary shock-testing machineto the base plate 71. The rotary assembly consists of bearing assemblies75 which are attached to the platform structure 74, and which are usedto rotatably support the shaft 76. The shaft 76 may be one piece or havetwo parts that are connected together by a coupling 77 as shown in FIG.9, as was described for the shaft 18 for the embodiment of FIG. 1. Inpractice, multiple bearing units 75 can be used on each section of theshaft 76 to minimize its deflection and to allow it to be rotated at thehighest operating speed that the machine is designed to operate.

A flywheel 78 is firmly attached to one end of the shaft 76 and a drivepulley 80 is attached to an opposite end of the shaft 76 as shown inFIG. 9. The flywheel 78 is provided with the central shallow groove 79around its periphery. The shaft 76 and thereby the flywheel 78 isrotated by an electric motor 81 via a belt 82 and the motor pulley 83,FIG. 9. The electric motor 81 is firmly attached to the base plate 71.The speed of the electric motor 81 can be controlled by a controller,such as a computer (not shown) as is commonly done in various machinery.

The mechanical rotary shock testing machine 70 is also provided with a“testing platform disc” 84 (similar to the disc 15 in the embodiments ofFIGS. 1-8), over the frontal surface 85 of which the components to betested 86 are generally attached. The testing platform disc 84 isrigidly attached to a shaft 87, which is supported by bearings 88mounted over a rigid platform structure 91, which is in turn fixedlyattached to the base plate 71. In practice, multiple bearing units 88can be used on each section of the shaft 87 to minimize its deflectionand to allow it to be rotated at the highest operating speed that themachine is designed to operate.

The shaft 87 is also provided with a wheel 89, which is fixedly attachedto the shaft 87. The wheel 89 is also provided with a peripheral groove90 similar to the groove 79 on the periphery of the flywheel 78. Themechanical rotary shock testing machine embodiment 70 shown in FIG. 9 isassembled such that the shafts 87 and 76 are essentially parallel andsuch that the wheel 89 and the flywheel 78 are essentially lined up,with the grooves 90 and 79 on the wheel 89 and flywheel 78,respectively, facing each other. The wheel 89 and the flywheel 78 arealso positioned very close to each other with a minimal clearanceseparating them. The clearance, depending on the desired shock loadingtest and the moment of inertial of the components (about the axis ofrotation of the shaft 87) to be tested, can be of the order 1-4millimeters, and can be adjustable. The clearance can be adjustable bythe movement of the rigid platform structure 91.

During a spin acceleration test, the drive motor 81 is first used tobring the flywheel 78 to the desired spin rate to which the testingcomponents 86 are desired to be accelerated to. At this point, the testplatform disc 84 and thereby the testing components 86 are stationary.At this point, a strip of a relatively hard rubber or leather or thelike high friction but relatively flexible material, which may have asharpened or tapered tip (not shown) is suddenly fed between theflywheel 78 and the wheel 89, such as through the facing grooves 79 and90. If the thickness and material properties of the high friction stripand the amount of clearance between the flywheel 78 and the wheel 89 areselected properly, then the strip will engage the flywheel 78 and thewheel 89, and quickly accelerate the wheel 89 to the rotary speed of theflywheel 78.

The wheels will then grab the strip and pull it between the two wheelswhile compressing it to fit their opening gap. By providing relativelyrough surface on the flywheel and the friction disc, the flywheel wouldrapidly accelerate the friction wheel to its own speed. The rate ofacceleration is dependent on the friction forces generated by the hardrubber or the like strip, which is dependent on the strip hardness,viscoelasticity and thickness, and the provided clearance between theflywheel 78 and the wheel 89.

It will be appreciated by those skilled in the art that depending on theamount of friction to be generated between the high friction strip andthe surfaces of the flywheel 78 and the wheel 89, the high frictionstrip may be relatively small and fit between the grooves 79 and 90, orwhen larger friction forces, i.e., higher spin acceleration rates aredesired, a wider band of such high friction strip may be used betweenthe surfaces of the flywheel 78 and the wheel 89. In general, thesurfaces of the flywheel 78 and the wheel 89 are desired to berelatively rough and non-slippery. The surfaces of the flywheel 78 andthe wheel 89 may also be covered by high friction materials such as hardrubber to further increase friction and achieve higher spin accelerationrates. In general, when higher spin acceleration rates are desired, thegrooves 79 and 90 may be eliminated to allow the introduction of widerhigh friction strips between the flywheel 78 and the wheel 89.

It will be appreciated by those skilled in the art that the sensor 40,as shown in FIG. 1, used for measuring the rotary position, velocity andacceleration of the testing platform disc 15 may also be positionedsimilarly, such as under the testing platform disc 84 of the mechanicalrotary shock testing machine 70 of FIG. 9 to make the same measurementswith the aforementioned optical or the like method. Alternatively, or asa second means of making the same measurement of the rotary position,velocity and acceleration of the testing platform disc 84, themechanical rotary shock testing machine 70 of FIG. 9 may be providedwith slip rings 92, which can be attached as shown in FIG. 9, with onering fixed to the shaft 87 and the other ring fixed to the bearing 88,thereby being kept fixed to the machine structure.

In the spin acceleration shock testing machine described above and theresulting embodiments shown in the schematics of FIGS. 1-9, the spinacceleration occurring during firing of spin stabilized rounds issimulated by the spin deceleration of a spinning test object in theembodiments of FIGS. 1-8, and by providing spin acceleration shockloading to a stationary testing platform disc (84 in the embodiment ofFIG. 9) to a prescribed spin rate at a preset acceleration rate. Methodsfor the design of such spin acceleration shock testing machines and theresulting basic apparatus embodiments were also described in detail.

However, since during firing of munitions in rifled barrels, themunitions is subjected to linear acceleration in the direction of itstravel inside the barrel as well as the aforementioned spin accelerationabout the direction of its travel, therefore, also provided are methodsof designing and constructing shock loading machines that can impart acombination of linear acceleration shock loading as well as spinacceleration shock loading to the munitions systems and/or itscomponents to be tested. It will be appreciated by those skilled in theart that in munitions firing in rifled barrels, the spin accelerationrate and the linear acceleration rates are related and are notindependent with the relationship being dependent on the pitch of therifling inside the barrel.

Such shock testing machines that can subject test components and systemsto a combination of high rotary and linear acceleration shock loadingsimilar to those experienced during firing by rifled barrels and atypical resulting shock testing machine is described using theembodiment 100 of FIG. 10. All components of the embodiment 100 of FIG.10 are identical to those of the embodiment 70 of FIG. 9, except for thetesting platform disc 84 assembly, which is not shown in the schematicof FIG. 10.

In the mechanical shock testing machine 100, a similar “testing platformdisc” 92 (84 in the embodiment of FIGS. 9 and 15 in the embodiments ofFIGS. 1-8) is also provided, over the frontal surface 93 of which thecomponents to be tested 94 are generally attached. The testing platformdisc 92 is rigidly attached to the shaft 95, FIG. 10, which is supportedby bearings 96, which are mounted over the rigid platform structure 97,which is in turn fixedly attached to the base plate 71. In practice,multiple bearing units 96 can be used on the shaft 95 to minimize itsdeflection and to allow it to be translated and rotated at the highestoperating speed that the machine is designed to operate.

In the above embodiments, the testing platform disc shafts (87 in theembodiment of FIGS. 9 and 18 in the embodiments of FIGS. 1 and 5) areattached to the machine support structure (91 in the embodiment of FIGS.9 and 14 in the embodiment of FIG. 1) by rotary bearings (88 in theembodiment of FIGS. 9 and 19 in the embodiment of FIG. 1), which allowthe shafts to freely rotate but not translate relative to the bearings.However, in the embodiment 100 of FIG. 10, testing platform disc shaft95 is attached to the rigid platform structure 97 by bearings 96, whichallow the shaft 95 to freely rotate as well as translate along rotaryaxis of the shaft. A similar friction wheel 102 (89 in the embodiment ofFIG. 9 but without the peripheral groove 90) is also provided andsimilarly fixedly attached to the shaft 95).

A relatively soft and lightly preloaded compressive spring 103 can beprovided between the friction wheel 102 and the bearing 96 as shown inFIG. 10 to keep a cam follower 99 in continuous contact with the surfaceof the cam 101, which is provided on the back surface 104 of the testingplatform disc 92, as is shown in the schematic of FIG. 10. The camfollower 99 is attached to the base plate 71 by the support 98. The cam101 is provided at a radial distance on the indicated back surface 104of the testing platform disc 92 so that as it is rotated during spinacceleration shock loading as was described for the embodiment of FIG.9, testing platform disc 92 is simultaneously accelerated forward,thereby applying a combined spin acceleration and linear acceleration tothe munitions system or components 94 that are tested. As a result, themunitions system or components 94 that are tested are subjected to ashock-loading event that is very similar to that experienced duringfiring by rifled munitions.

The view of the back surface 104 of the testing platform disc 92 of themechanical shock testing machine embodiment 100 of FIG. 10 is shown inFIG. 11. The view of the testing platform disc 92 in the direction ofthe arrow 105 is shown in FIG. 12. As can be seen in the back surface104 view of FIG. 11, the cam 106 (101 in the schematic of FIG. 10) isseen to be positioned at a fixed radial distance from the rotating shaft95 of the testing platform disc 92. Initially, while the testingplatform disc 92 is stationary, the cam follower 99 is positioned closeto the start 107 of the (rising) cam surface 108. Then as the frictionwheel 102 (FIG. 10) engages the flywheel 79 (FIG. 9) by the introductionof the aforementioned strip of a relatively hard rubber or leather orthe like high friction but relatively flexible material which can have asharpened or tapered tip (not shown) between the flywheel 79 and thefriction wheel 102, the testing platform disc 92 is rotationallyaccelerated in the counterclockwise direction as seen in the view ofFIG. 11. As a result, the cam follower 99 (FIGS. 10 and 12) begins toroll over the surface 108 (FIGS. 11 and 12) of the cam 106 (101 in theschematic of FIG. 10), thereby pushing (linearly accelerating) thetesting platform disc 92 in the direction of the arrow 111 shown in FIG.10, while the testing platform disc 92 is also being rotationallyaccelerated as was previously described for the embodiment 70 of FIG. 9.The testing platform disc 92 is accelerated in the direction of thearrow 111, FIG. 10, until the cam follower 99 reaches the flat surface109 (FIGS. 11 and 12) of the cam 106, by which time the cam 106 wouldhave translated the testing platform disc 92 a distance 110 shown inFIG. 12.

It will be appreciated by those skilled in the art that when the testingplatform disc 92 is to be rotated in the clockwise direction furtherthan the provided flat surface 109 (FIGS. 11 and 12) for the camfollower 107 to travel, then the flat surface 109 may be extended asneeded as shown by the dashed lines in FIG. 11 and as indicated by thenumeral 112.

It will also be appreciated by those skilled in the art that the slopeof the surface 108 of the cam 106, FIGS. 11 and 12, relates therelationship between the spin acceleration of the testing platform 92and its linear acceleration in the direction of the arrow 111, FIG. 10,i.e., higher the slope of the surface 108, higher linear accelerationwould result for a given rotary (spin) acceleration of the testingplatform 92 and thereby that of the munitions system or components beingtested.

While there has been shown and described what is considered to bepreferred embodiments of the invention, it will, of course, beunderstood that various modifications and changes in form or detailcould readily be made without departing from the spirit of theinvention. It is therefore intended that the invention be not limited tothe exact forms described and illustrated, but should be constructed tocover all modifications that may fall within the scope of the appendedclaims.

What is claimed is:
 1. A linear and rotary shock-testing machinecomprising: a base; a shaft rotatably and translationally movablerelative to the base; a test disc for holding one or more specimens tobe tested, the test disc being rotatable with the shaft; one of a camand cam follower fixed relative to the base; and an other of the cam andcam follower fixed to the test disc, wherein the shaft being driven toprovide a rotational shock to the one or more test specimens; and thecam is shaped such that the cam follower follows the cam to urge thetest disc into a translational motion while rotating to providetranslational shock to the one or more specimens.
 2. The linear androtary shock-testing machine of claim 1, further comprising a biasingelement for biasing the cam follower into engagement with the cam. 3.The linear and rotary shock-testing machine of claim 1, furthercomprising a first shaft rotatable relative to the base, the first shaftbeing driven to rotate; a first wheel rotatable with the first shaft;the shaft being a second shaft rotatable relative to the base; a secondwheel rotatable with a first portion of the second shaft; and the testdisc being rotatable with a second portion of the second shaft; whereinthe first and second wheels are aligned with each other such that thesecond wheel is driven by the first wheel when a material is introducedinto a gap between a surface of the first wheel and a correspondingsurface of the second wheel to provide the rotational shock.
 4. Thelinear and rotary shock-testing machine of claim 3, further comprisingone or more bearings for rotatably supporting each of the first andsecond shafts.
 5. The linear and rotary shock-testing machine of claim4, wherein the one or more bearings comprises two or more bearings andeach of the first and second shafts comprise two or more shaft portionscorresponding to each of the two or more bearings, and furthercomprising a coupling for coupling each of adjacent two or more shaftportions together.
 6. The linear and rotary shock-testing machine ofclaim 3, further comprising a motor operatively connected to the firstshaft for rotatably driving the first shaft.
 7. The linear and rotaryshock-testing machine of claim 3, wherein the first wheel is a flywheel.8. The linear and rotary shock-testing machine of claim 3, wherein thesecond wheel is a friction wheel.